Temperature For Annealing

Theoretically, annealing should be
accomplished at a temperature at just slightly above the critical
point. However, in practice the temperature is raised to a higher
point in order to allow for the solution of the carbon and iron to
be produced more rapidly, as the time required to produce complete
solution is reduced as the temperature increases past the critical
point.

For annealing the simpler types of low-carbon steels the following
temperatures have been found to produce uniform machining conditions
on account of producing uniform fine-grain pearlite structure:

0.15 to 0.25 per cent carbon, straight carbon steel.--Heat to 1,650 deg.F.
Hold at this temperature until the work is uniformly heated; pull
from the furnace and cool in air.

0.15 to 0.25 per cent carbon, 1-1/2 per cent nickel, 1/2 per cent
chromium steel.--Heat to 1,600 deg.F. Hold at this temperature until
the work is uniformly heated; pull from the furnace and cool in air.

0.15 to 0.25 per cent carbon, 3-1/2 per cent nickel steel.--Heat
to 1,575 deg.F. Hold at this temperature until the work is uniformly
heated; pull from the furnace and cool in air.